Joints were meant to move

By Pat Ohlendorf , Bulletin University of Toronto Monday,
October 20, 1980

Osteoarthritis, or
degenerative arthritis, has been found in the bones of cavemen and even
dinosaurs. It is the gradual wearing away of joint cartilage, an irreversible
process because the damaged joint responds not by generating new cartilage but
by producing bony outgrowths and fibrous, or scar, tissue. Sometimes no
cartilage is left at all and the joint becomes too stiff and painful to move.
Drugs can't cure the arthritis, and doctors have been reduced to prescribing
heating pads and aspirin to dull the pain, symptom of the disease. In the past,
surgeons turned to fusing the worn-out joint which stops the pain but also makes
it permanently rigid, or, more recently, to replacing the joint with an
artificial one. Some arthritis sufferers who haven't been helped medically have
tried acupuncture, chiropractic, hypnosis, and even copper jewellery and other
home remedies.

Although degenerative arthritis
can develop spontaneously, more often it is a response to previous damage.
Other joint diseases such as septic arthritis (infected joints) can set it off,
as can deformities and injuries. Thus, despite its reputation as one of the
agonies of aging, degenerative arthritis can afflict anyone several years after
joint damage.

Also, according to Dr. Robert
Salter, professor and head of Orthopaedic surgery at U of T and senior
Orthopaedic surgeon at the Hospital for Sick Children, degenerative arthritis is
sometimes an iatrogenic (doctor-produced) disease. Through his animal research
he has shown that when a joint is kept still in a cast or splint for a long time
as a form of treatment, several things can go wrong. When a fracture involves a
joint surface, prolonged immobilization can cause the fracture in the cartilage
to be filled in with scar tissue which later breaks down and leads to
arthritis. Or the membrane around the joint can stick to the cartilage like
scotch tape in certain areas. Then the joint fluid, the only source of nutrients
for cartilage, cannot reach those spots which soon die. Not only injured joints
may be subjected to this deterioration but also healthy ones which are often
immobilized for several weeks or months when an adjacent bone is fractured.

The aim of Salter's current
laboratory research is to prevent degenerative arthritis. Through almost a
decade of careful animal studies, he has been proving that, contrary to
long-standing medical belief, cartilage can regenerate. The key is motion-in
fact, "continuous passive motion," a completely new concept. He has discovered
that if joints are moved continuously for at least one week after an operation,
defects in cartilage heal with new cartilage and subsequent arthritis is
unlikely. Some day, due to Salter's work, the maxim that tissues must be at
rest to heal may be as outmoded as blood-letting, and at least some types of
degenerative arthritis may be understood as unavoidable, rather than inevitable,
consequence of joint damage.

Robert Salter has throughout his
career questioned empiricism and dogma. He describes his attitude as what
Voltaire called "the spirit of constructive discontent". Today his concepts
carry weight, with the credibility of 25 years as an internationally respected
researcher, clinician and teacher behind him. A Fellow of the Royal Society of
Canada, Companion of the Order of Canada, past president of the Royal College of
Physicians and Surgeons of Canada and a winner of numerous honours including a Gairdner International Award for Medical Science, Salter is perhaps best known
to Orthopedic colleagues for the operation he designed in 1957 to correct
congenital hip dislocations, which was promptly designated (by others) "the
Salter operation".

When I arrive at his office at
the Hospital for Sick Children for an interview, Salter is still in surgery, so
I find a seat outside in the Orthopedic clinic waiting area. Soon a tanned,
grey haired figure in OR greens and white coat strides through rapidly, followed
by a retinue of young men in white coats-and wearing ties-who are struggling to
keep up with him. He flings open the office door; they all go into a huddle
inside; the door shuts. A few minutes later it opens gently and the senior of
the three secretaries ushers me in.

Salter looks as vigorous
standing still as in motion. The eyes behind the professorial glasses appraise
me steadily and warmly; the hand that grasps mine is firm. He exudes confidence
and authority.

"How," I ask, when we have
settled ourselves in his inner office, did you conceive the idea of continuous
motion? Isn't it a pretty radical thing to do-to move injured joints
continuously?"

"Radical, yes," he repeats,
picking up his pipe and beginning the mesmerizing rituals of tapping, filling
and drawing, "but innovative and perhaps imaginative too, because it goes
against the time honoured concepts of how to manage injured joints."

After his description of current
methods of joint treatment, I launch into the topic that is uppermost in my
mind: "Are you getting cartilage to regenerate in humans yet?"

"Everybody wants to know that,"
he replies with an understanding smile.

"They don't want to know about
all the research that went on before-just where to push the buttons for clinical
applications of the concept."

I laugh with him. He leans back
in his swivel chair and pauses effectively. "In answer to your question-yes, we
have started applying continuous passive motion to human patients."

Even as a medical student,
Salter was, as he puts it, "a mover rather than a rester" and a challenger of
the conventional wisdom. Against his team doctor's recommendations, he treated
his own three football injuries (torn ligaments in both ankles and a dislocated
collarbone) not by plaster casts and rest but by taping them and continuing to
play end for the U of T's medicine team. "I simply felt that joints were meant
to move," he recalls, "and besides, I wasn't keen on sitting out the rest of the
season." Although Salter might not recommend such strenuous activity for his
patients today, his own experiences made him curious.

" I began thinking of motion as
a spectrum," he continues. "At one end is complete immobilization-a cast. In
the middle of the spectrum is intermittent motion-either everyday activity
(active motion) or passive movement of joints by a physiotherapist. At the
other end of the spectrum is continuous motion." Other researchers had been
investigating intermittent motion-in animals by cage activity and in clinical
studies by getting patients up and about soon after surgery-and the results were
somewhat encouraging. But no one had tried continuous motion. To investigate
that extreme, a mechanical device was needed because muscles tire. Hence the
concept of "continuous passive motion".

Salter had a hunch that
continuous motion would not be painful. His own joint injuries had taught him
what arthritis sufferers know: that a joint is stiff and painful in the morning,
after it has been at rest for several hours, but the stiffness and pain
gradually disappear as it is moved. If, he speculated, a joint could be set in
motion immediately after surgery, it might prevent pain and stimulate better
healing.

Using a machine for rabbits he
had designed and bioengineers at the hospital had built, he first ensured that
continuous motion itself would do no harm. He suspended healthy rabbits in
slings and simply moved their knees mechanically in slow revolutions (one
complete cycle about every 45 seconds) for several weeks. The animals ate,
drank and slept as usual, and appeared comfortable. "The younger rabbits
continued to gain weight and the adults maintained their weight," says Salter.
"That's a good indication of the animal's health, because if a rabbit is sick or
uncomfortable it won't eat. We watched the animals very, very closely because
we didn't want to cause them harm."

Next, he set out to determine
what kind of tissue forms in injured cartilage with different types of
treatment. He drilled narrow holes in the cartilage and bone of the right knee
joints of 120 rabbits. One-third of the rabbits were then treated by plaster
casts (immobilization); one-third were put into cages (intermittent motion); and
the remaining third were placed in the machine before their anesthetic had worn
off (continuous passive motion). When the rabbits from each group were
sacrificed weeks and months later, their joints were examined through a
dissecting microscope, light microscope and electron microscope, and new tissues
were analyzed biochemically. Subsequent experiments followed the same model of
three groups of rabbits; most important for clinical application was the study
of joint fractures.

The results of the experiments
show a strong correlation between motion and healing. The rabbits that were
treated by casts fared the worst. None, when examined six months later, had
formed new cartilage. If the fractures had closed at all, they had done so with
scar tissue and already there were many signs of arthritis. The rabbits left to
hop in their cages were somewhat better off. They also had scar tissue
adhesions and signs of arthritis, but 20 percent had formed new cartilage. The
rabbits treated by continuous passive motion, however, had no scar adhesions,
significantly fewer signs of degenerative arthritis, and 80 percent of them had
developed new cartilage.

Salter describes these results
with scientific understatement, referring to the new cartilage as "tissue
comparable to hyaline cartilage". ("Hyaline" refers to the translucent,
glass-like appearance of joint cartilage.) To an observer, however, the new
tissue is the real thing. The joints treated by continuous motion are as smooth
and shiny as normal joints while those from the other groups are grossly
deformed. Through the microscope the new cartilage is indistinguishable from the
surrounding cartilage while the other groups show striated scar tissue,
deformities and gaps. In histochemical tests, too, the new tissue reacts with
the staining patterns characteristic of hyaline cartilage.

Although the biochemical and
cellular details of cartilage regeneration are not yet fully understood, Salter
has discovered that underlying bone as well as cartilage must be affected if new
cartilage is to form. Certain embryonic-like cells located in bone appear to be
capable of differentiating into bone, scar tissue, or cartilage, depending on
the stimulus. And for some reason motion encourages these cells to form bone
where bone should be and cartilage where cartilage should be. Lack of motion,
on the other hand, only causes rampant growth of scar tissue.

When Salter was certain of the
value of continuous passive motion in the laboratory, he asked Professor David
James and John Saringer of the University's Department of Mechanical Engineering
to build a device that would provide continuous passive motion for the human
knee joint.

The first patient to try the new
machine was 16-year-old Michelle who had been born with a condition that caused
her knee caps to dislocate easily. In July 1978 she had fallen down a flight of
stairs, severely injuring her left knee. Extensive repair work, after which her
lower limb was done by a surgeon in her hometown in southern Ontario. However,
the knee only seemed to get worse. When Michelle was admitted to Sick Kids, in
July 1979, she couldn't support any weight on her left leg. She had not attended
school since January and had been on crutches for a year. Her knee was swollen,
red and painful and the muscles attached to it had atrophied. She was unable to
straighten her leg and could bend her knee only 25 degrees of the normal
150-degree range of motion. Although she was not the ideal patient for what was
essentially a clinical trial of a new method of treatment, Salter felt that
Michelle needed something more than conventional methods.

He operated, removing the
abnormal bony spurs and massive scar adhesions that had built up since the
previous operation, and rebuilt her joint using her own tissues. Then, as with
the rabbits, before Michelle's anesthetic had worn off, he attached her left
foot to the pedal of the machine, which began moving her lightly bandaged knee
passively in the slow revolutions that continued night and day for almost three
weeks.

When I phoned Michelle, she was
eager to talk about her unusual experience at Sick Kids. "I was scared when Dr.
Salter told me what he was planning to do," she admits. "I remembered the pain
when I woke up from my other operation and I thought, 'Oh wow, this is going to
be twice as bad because the knee will be bending too!'."

But what sounded like a torture
device actually turned out to be pleasant. "When I woke up, the first thing I
saw was my knee bending and I was almost crying because it didn't hurt at all!
I never had to ask for needles for pain because I didn't have any. I just
couldn't get over it! It felt so good to get it bending again."

Michelle fell asleep easily,
lulled by the slow, regular motion; she became so used to the machine that she
even had to be weaned off it gradually when it came time to go home. "My life
has changed so much since then," Michelle says. "It's just a normal knee now."

Although Salter's face lights up
as he recalls the details of Michelle's treatment, he is cautious about making
long range claims. But since she still has no pain or stiffness in her knee
more than a year after her operation, and since her X-rays are perfectly normal,
he admits the chances are good that she, like the many continuous-passive-motion
rabbits before her, has developed new hyaline cartilage and that she will
continue to have excellent function in her knee for the rest of her life.

Increasingly, patients
recovering from other types of surgery are encouraged to move about early but
Orthopaedic practice still includes putting joints in casts for several weeks or
months. "Heart muscle moves continuously after open heart surgery," Salter
observes, "and the incision heals. Same thing with the lung and bowel. The
trouble is, it's been done for centuries." Convincing other surgeons to change
old habits, Salter realizes, will require good results with many human
patients. His clinical applications are just beginning. U of T engineers have
built two new machines, one for the elbow and one for the finger, and so far
three patients since Michelle have been treated by continuous passive motion.

Meanwhile, Salter's laboratory
work is taking new turns within arthritis research. He has just completed
studies on septic arthritis and torn ligaments and is confident that patients
with these problems can be treated successfully by continuous passive motion.
In addition, Salter and his research fellows are currently trying to simulate
rheumatoid arthritis in rabbits, in order to study the effect of motion on this
condition.

Unlike his rabbits and patients,
Salter himself seems to thrive on continuous active motion. Although his
research is a high priority and he hopes to devote himself to it full-time when
he retires in 10 years, at present he also has teaching responsibilities,
administrative duties, frequent visiting professorships and scientific meetings
and a demanding clinical practice-and still includes time for his wife Robina,
an author, and their five
children, David, Nancy, Jane, Stephen and Luke. He jokes about his tight schedule, even seems proud of living on one
meal a day and five hours of sleep per night and getting up to read or write at
4:30 every morning (except Sundays, when he sleeps in till seven). Two rare
indulgences in this life-long marathon seem to be his hobby of heraldry and his
30-year-old sports car, a snazzy topless Allard, which he drives to work year
round regardless of the weather.

As for Michelle, she's content
to have a normal knee. After swimming, cycling, roller-skating, and playing
tennis all summer, she's looking forward to winter so she can try out her new
ski!